The present invention relates to automotive bumper systems having beams and energy absorbers located on faces of the beams.
Many vehicle designs use energy absorbers positioned on a face or front surface of a steel bumper beam to improve energy absorption of a bumper system. The energy absorbers provide an initial level of energy absorption for low impact, including reducing damage during low impact, and also provide a supplemental level of energy absorption during high impact (i.e. before and-at the time that the beam and vehicle begin to absorb substantial amounts of energy). Usually, the energy absorbers are fastened to the bumper beam with fasteners that assure accurate positioning of the energy absorber on the beam. The reasoning includes accurately positioning the energy absorber on the bumper beam to assure consistent performance, as well as to assure accurate positioning for aesthetics and assembly (e.g. to assure a good fit of the front-end fascia over the energy absorber and beam during assembly).
However, improvements are desired in terms of temporary and permanent attachment, and for improved and more reliable energy absorption. Typically, attachment of the energy absorbers to bumper beams requires a plurality of fasteners. This is disadvantageous since fasteners require manual labor to install, which can add undesirably to cost. Also, the fasteners can result in localized and non-uniform stress distribution during impact, resulting in inconsistent collapse of the bumper system and poor energy absorption on impact. Further, fixing the energy absorber to the beams results in an inability of the energy absorber to shift and adjust to non-perpendicular and uneven loads transmitted from the impacting bodies. At the same time, depending on the bumper system, sometimes shifting of an energy absorber is not good since it can result in unpredictable, premature and non-uniform collapse, resulting in poor or inconsistent energy absorption by the bumper system.
For all of the above reasons, there is a desire for bumper systems that yield a better, more consistent, more reliable, and greater impact energy absorption, both for low and high impact events, and also for square and skewed impact directions. Also, there is a desire for improvements facilitating assembly of an energy absorber to a beam, with lower cost and fewer parts, and with less labor. Still further, there is a desire for energy absorber designs that allow adjustment and tuning for optimal front-end and corner impact strengths, even late in the bumper development program, and yet that does not require expensive or complex molding techniques or assembly techniques. Still further, there is a desire for energy absorber designs that are adaptable for use with many different bumper beam cross-sectional shapes and sizes. Also, energy absorber designs are desired that are flexible and usable on non-linear bumper beams having different curvatures and longitudinal sweeps, and having different cross sections.
In one aspect of the present invention, a bumper system for vehicles includes a bumper beam having a continuous cross section with a front surface that extends vertically when the bumper beam is in a car-mounted position, and a polymeric energy absorber having a length. The energy absorber includes a rear surface abutting the front surface of the bumper beam. The energy absorber has multiple box-shaped sections and also has interconnecting sections positioned along the length that interconnect adjacent ones of the box-shaped sections. The box-shaped sections of the energy absorber, when cross-sectioned by a transverse plane that extends perpendicular to the length, include a top U-shaped section formed by top parallel legs and a top vertical leg, and further include a bottom U-shaped section formed by bottom parallel legs and a bottom vertical leg. The box-shaped sections further include end walls at each end that are attached to the parallel and vertical legs of the top and bottom U-shaped sections to close ends of the box-shaped sections and to stabilize the top and bottom U-shaped sections relative to each other. The interconnecting sections include a tying wall that connects the end walls together, whereby the box-shaped sections provide a stable and reliable energy absorbing mechanism with the energy-absorbing U-shaped sections being stabilized by the end walls and with adjacent box-shaped sections being held together by interconnecting sections.
In yet another aspect of the present invention, a bumper system for vehicles includes a bumper beam having a continuous cross section with a front surface that extends vertically when the bumper beam is in a car-mounted position. A polymeric energy absorber has a length and includes a rear surface abutting the front surface of the bumper beam. The energy absorber has first, second, third, and fourth parallel walls that extend horizontally, the first parallel wall being at a top location and the fourth parallel wall being at a bottom location. The energy absorber further includes a top front wall interconnecting the first and second parallel walls to form a rearwardly-facing U-shaped top channel, and includes a bottom front wall interconnecting the third and fourth parallel walls to form a rearwardly-facing U-shaped bottom channel, the energy absorber further having stabilizing walls that interconnect at least the first and fourth parallel walls to stabilize the top and bottom channels on the bumper beam.
In yet another aspect of the present invention, a bumper system for vehicles includes a bumper beam and an energy absorber for the bumper beam. The bumper beam has a front surface that extends vertically when the bumper beam is in a car-mounted position and has a pair of attachment features. The polymeric energy absorber has a length and includes a rear surface abutting the front surface of the bumper beam. The energy absorber further has a pair of protrusions adapted to engage the attachment features to temporarily loosely hold the energy absorber on the bumper beam during assembly of the energy absorber to the bumper beam.
In a narrower aspect, the protrusions include a hooked end, and are integrally molded as contiguous material of the energy absorber. Also, the protrusions extend from an upper portion of the energy absorber and hook onto a feature on a top of the bumper beam.
These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.